Hi Damo,
Bummer that the Tonerider JB Pups (and Entwistle also) are a bigger size to the PB JB pups.
Do you have access to a Dremel rotary tool and small chisel? You could trace the tonerider bridge shape onto the body and then use the small sanding drum to carefully sand out the mounting screw curves. To get a wider pup route you will need to use a chisel (or file) to get the square ends.
This is quite difficult, but possible. I had to create a cavity for an Entwistle JB pup for my Tele Bass that I just finished. I made a template for a router, but still needed Lots of chiseling, filing and sanding to get the square ends and the semicircles to the correct shape.
See the link at https://www.buildyourownguitar.com.a...l=1#post226952.
The same will have to be done to the pickguard for the neck pup. (Not sure if other "fender" pickguard would have the same problem. Even if the pup fitted the neck probably would not!!)